Installing OwnCloud 9

consider me as beginner with Linux. I struggle with installing the latest version of OwnCloud. When I try to install OC via the OMV plugin manager, it installs version 6 of OC.
What I tried:

Upgrading manually vie the OC upgrade manual. Since i am on version 6 and the manual advises against skipping major releases in the upgrade process, this is a bit of a pain in the ass. Also, i would like to have OC managed in the packet manager for easy further upgrades...(apart from that the upgrade process failed and i was not able to access the web-config page anymore, idk the failure anymore).

Installing version 9 of OC by adding the package to the repository, like told here. Installation seemed to be successful, but the OC-plugin is not visible in the OMV web gui.
And because i don't know much about Linux, i did not know what to do.

So i googled a bit and found a few topics in this forum, but every link from google redirects me to the main page. There should be a guide from the user tekkb, but i was not able to access the thread...